Designed for the pentax k 5 ii digital slr the bg 4 battery grip allows extends shooting time via the option to use an additional d li90 battery plus the convenience of being able to use 6 standard aa batteries as an alternative a separate battery tray is included for either option it also features a vertical release button depth of field preview switch front and rear control dials and buttons for exposure lock autofocus and iso control for when youre using the camera in portrait format